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The Metrics of Space: Tactical Level Design

By introducing an enemy into the example used in Figure 20, we can begin to evaluate how the level geometries modify line of sight, view angle and evasion / approach vectors. Figure 21 is an example of the player moving forward along a tight corridor into an open space.

Figure 21

As the camera frustum has been occluded by the level geometry, the player is unaware of the patrolling enemy ahead. In this example, the player is the most disadvantaged. The level geometry is reducing their possible evasion vectors. By removing the player's possibility to strafe, the enemy has the advantage of requiring fewer correction cycles to target the player.

In this example, the player will need to rush into unknown space in order to engage the enemy. They will be hesitant to do this, as it will require changes to GFOV and world position in order to engage. Further to this, as the room has been occluded, they will have not situational awareness in this environment -- they may even believe that they are moving into another tight hallway.

There is, however, an upside; confined spaces are sometimes beneficial for the player, as it reduces the possible amount of approach vectors that an enemy can use against them. The trade-off, though, will always be a reduction in the possible evasive movement vectors, so evaluating this particular scenario requires more knowledge of the enemies' behaviors.

Figure 22

If we change the player's position with the enemy's position, we have a significantly different type of encounter -- one that favors the player for all of the same reasons that the enemy was favored in the previous encounter (Figure 22). This is another extension of the notion of compression and funneling that I have discussed previously.

Corridors like those depicted in Figure 22 are choke points which cause compression on the player -- when compressed, the player will feel extremely anxious, and move quickly to get out of this environment, especially in deathmatch type scenarios where human players will exploit these choke points.

Figure 23

Figure 23 is a demonstration of how we can modify the player's tactical abilities and subsequent emotional state by introducing certain level geometries. In frame 1 of Figure 23, the player is moving forward through the frame, and has two enemies approaching them from a diagonal vector, just outside of their line of sight. This example is similar to that of Figure 21; however, when the player goes to engage enemies by changing their view frustum (and/or their world position) they have reoriented themselves into a corner, hence compromising the available space that they have for evasive maneuvers. (Figure 24)

Figure 24

Forcing enemies through choke points will always be advantageous for the player. Figure 25 modifies the scenarios depicted in Figure 24 to turn the tactical advantage towards the player. Frame 2 of Figure 25 demonstrates how an occluding device can be beneficial for the player from a strategic perspective. In this example, the player has two approach vectors to monitor. As there is only one enemy, they can use the either one of the two approach vectors as an evasion vector to force to the enemy into another choke point if they need to.

Figure 25

Figure 25 can be further modified with level geometry to add additional choke points (Figure 26). However, this will start to work against the player, as they have far too many possible approach vectors. We can think of this scenario in terms of "closing off space" -- a tactic that players use as a type of checklist to ensure that that they systematically closed off possible ambush vectors before moving onto the next game space.

Figure 26

In Figure 27, we have the same amount of choke points as in Figure 26; however, the player is able to systematically close each one of these off as they move through. In Figure 26, the player needs to manage three different potential approach vectors at any one time, whilst in the linear space of Figure 27, they only every have to manage two at a time. Further to this, they can incrementally close off these spaces to reduce this number further.

Figure 27

As the player moves through the environment as depicted in Figure 27, they begin to close off space, preventing possible ambush (under normal circumstances at least). Games such as Dead Space purposely break this rule in order to keep the player in a constant stage of anxiety: